File Description:TDS Boeing 727-100F United States Postal Service (N413EX). The United States Postal Service, also known as the Post Office, U.S. Mail, or Postal Service, often abbreviated as USPS, is an independent agency of the United States federal government responsible for providing postal service in the United States. It is one of the few government agencies explicitly authorized by the United States Constitution. Model design by Hiroshi Igami. Flight dynamics design by Nick Wilkinson and David Biggar. Master textures by Kyle Schurb.